Field of the Invention
The present invention relates to a method for producing a shaft having at least one substantially annular bearing seat and at least one unbalance portion. The present invention further relates to a shaft of this type having at least one substantially annular bearing seat and at least one unbalance portion.
Description of the Background Art
In the prior art, a multiplicity of shafts having a variety of unbalance portions and bearing seats is known. In the automotive sector, in particular, such shafts are used as so-called balance shafts in internal combustion engines for the partial or full compensation of the free inertia forces. It is here known to provide the shaft with a bearing (in particular a roller or needle bearing) on the outer surface of the bearing seat and on the mutually opposite ends of the shaft. The shafts are here set in rotation in such a way that, as a result of the unbalance, at least a partial compensation of the free inertia forces is realized. Bearing seats of this type are usually provided on the shaft as solid disc-shaped or barrel-shaped components, on the outer surface of which a bearing is disposed. The unbalance portions, which are fixed relative to the bearing seat, here cause the main load to fall upon that side of the bearing seat which is facing the unbalance portions. In relation thereto, the loads on that side of the bearing seat which lies opposite the unbalance portions are comparatively low. Consequently, solidly configured bearing seats, at least in their load-free or low-load regions, are mechanically oversized. This ultimately leads to a higher consumption of resources and, in particular, to a higher fuel consumption of an internal combustion engine having such a shaft. In the light of this insight, shafts comprising solid bearing seats have been developed in the prior art, wherein, in the less loaded regions of the bearing seat, material has been removed or cut out in order to be able to appropriately reduce the weight of the bearing seat. Shafts of this type are disclosed, for instance, in printed publications DE 20 2007 018 991 U1 and DE 10 2009 035 684 A1, wherein material has there been removed there in the form of a circular arc, so that corresponding notches are obtained in the bearing seat. Bearing seats of this type have the drawback, however, that, for the arrangement of the bearing on the bearing seat, essentially a separate bearing ring has to be arranged on the bearing seat in order to be able to provide a continuous contact surface for the bearing.
Furthermore, efforts continue to be made to further reduce the weight of the known shafts, in particular of the bearing seat, in order thereby, on the one hand, to save on production material and, on the other hand, to reduce the fuel consumption of an internal combustion engine equipped therewith.